1. Field of the Invention
The present invention relates to a color reproduction characteristic display apparatus for displaying color reproduction characteristics defined in accordance with a device for mediating between image data and an image, for example, an input device for converting an image to image data, such as a color scanner and a digital scale camera, and an output device (including a display device for outputting or displaying an image on a display screen, such as a display unit and the like) for outputting an image in accordance with image data, such as a printing machine and a printer, and a color reproduction characteristic display program storage medium storing a color reproduction characteristic display program which causes a computer to operate as the color reproduction characteristic display apparatus.
2. Description of the Related Art
Hitherto, it is performed that an input device, for example, a color scanner or an electronic scale camera, is used to take an image (hereinafter, it is referred to as an original image) in to obtain image data, so that an reproduced image of the original image is obtained in accordance with the image data by a printing machine or a printer, or on a display screen. In this case, there are determined a color reproduction characteristic (profile) associating a color on the original image with a color on the image data, according to the input device, and a color reproduction characteristic (profile) associating a color on the image data with a color on the reproduced image, according to the output device such as a printing machine and a printer, and image data obtained from the original image by the input device is converted into image data suitable for the output device in accordance with both the color reproduction characteristics, so that the reproduced image is outputted in accordance with the image data for the output device. This feature makes it possible to obtain the reproduced image coincident with the original image in color.
The same matter as the above will occur between output devices. Next, there will be explained an example.
Hitherto, when a printing machine is used to perform a color image printing, it is performed that prior to the printing, a color printer and the like is used to create a proof image which is intended to be similar in color to an image to be printed by the printing machine. When the printer creates the proof image, detected are a color reproduction characteristic (a printing profile) describing a relationship between image data and a color of the actual printed matter, associated with a printing machine of interest, and a color reproduction characteristic (a printer profile) describing a relationship between image data and a color of an image to be actually printed, associated with a printer. Image data for printing is converted into image data for printers in accordance with the printing profile and the printer profile, so that a proof image is created in accordance with the image data for printers thus converted. Thus, it is possible to create a proof image that is coincident with the actual printed matter in color.
In order to obtain a proof image that is coincident with the actual printed matter in color in the manner as mentioned above, there is a need to determine with great accuracy color reproduction characteristics (profiles) of the input device and the output device. When the color reproduction characteristics (profiles) are determined, for example, in case of the input device, a color chart, in which color patches are arranged, is read by the input device and then converted into image data, and coordinates (CYMK values, or RGB values) of color spaces (a device color space: for example, a CMYK color space consisting of four colors of cyan (C), magenta (M), yellow (Y) and black (K), or an RGB color space consisting of three colors of red (R), green (G) and blue (B))) on the image data are determined. And the same color chart is measure by a spectrocolorimeter to determine coordinates (L*a*b* values or XYZ values) of a colorimetry color space (for example, L*a*b* color spaces or XYZ color spaces), and the coordinates on the device color space are associated with the coordinates on the colorimetry color space. Thus, it is possible to determine the color reproduction characteristics (profile) of the input device.
When the color reproduction characteristics (profile) of the output device is determined, image data, which corresponds to a color chart wherein color patches are arranged, is created, the output device outputs the color chart in accordance with the image data thus created, the color chart is measured by the spectrocolorimeter, and the coordinates of the color space (the device color space) on the image data are associated with the coordinates of the colorimetry color space. Thus, it is possible to determine the color reproduction characteristics (profile) of the output device.
The color reproduction characteristics of the input device and the output device are carefully determined, and the image data are converted in accordance with those color reproduction characteristics, nevertheless, various errors and main causes of fluctuations will cause a phenomenon in which colors are delicately different between the original image and the reproduced image, or between the printed matter and the proof image.
Under the circumstance as mentioned above, when it is evaluated as to whether a color of an image outputted from a color printer for example is properly reproduced as to a color of an original image which is read by a color scanner in form of image data, or when it is evaluated as to whether a color of an image outputted from a color printer is coincident with a color of an image on a printed matter, according to the earlier technology, a print output is actually carried out, and a weight is put onto only a point that the printed output image is evaluated. More in detail, according to the earlier technology, on the profile, for example, outlines of the profiles of both the color scanner and the color printer, or outlines of the profiles of both the printing machine and the color printer, are expressed on a two-dimensional plane, so that there is simply performed such an extent of evaluation that what color area is reproduced or not reproduced by the color printer. It is a present state that there is found no suitable one as a tool for scrutinizing on a profile and evaluating such detailed points that but not the rough evaluation on the severe vicinities of the outlines of the profiles, for example, on the center area in which profiles of both the color scanner and the color printer, or profiles of both the printing machine and the color printer, are sufficiently overlapped, how what color on the original image is coincident with or different from color on the reproduced image outputted by the color printer, or into what color image data having a certain value is converted through the printing machine or the printer, or how the printing machine and the color printer are coincident with or different from one another in color conversion.